The present invention relates to a vehicle air conditioning system equipped with a refrigerant circuit comprising an electrically operated compressor.
An air conditioning system in a passenger compartment of a vehicle such as an automobile has heretofore been equipped with an engine-driven compressor provided in an engine room outside the passenger compartment, and this compressor and an evaporator which configures a refrigerant circuit are provided in the passenger compartment to perform cooling. However, it has recently been considered to use an air conditioning system equipped with an electrically operated compressor driven by a power supply of a battery, especially in electric automobiles and hybrid automobiles.
In this case, the following method has been conventionally employed (e.g., refer to U.S. Pat. No. 3,152,154). The temperature of the evaporator, the amount of solar radiation into the passenger compartment and the temperature in the passenger compartment are loaded into a controller in the passenger compartment called an air conditioning amplifier provided in the passenger compartment. On the other hand, an inverter is provided outside the passenger compartment, for example, in the engine room, and the temperature at an exit of a heat exchanger of the refrigerant circuit, the outside air temperature and the like are loaded into the air conditioning amplifier via the inverter by serial communication, thereby calculating an operating frequency of the electrically operated compressor necessary for the air conditioning amplifier to perform air-conditioning in the passenger compartment. Then, the calculated data is sent to the inverter by serial communication, and the frequency of the operation of the electrically operated compressor is controlled.
However, in such a conventional control method, the amount of data is increased in the communication between the air conditioning amplifier provided in the passenger compartment and the inverter outside the passenger compartment, which complicates the control. Moreover, since the refrigerant circuit has to be controlled by the air conditioning amplifier, a control algorithm is complicated, and particularly when manufacturers of equipment inside and outside the passenger compartment are different, this poses a problem that cooperation is difficult in terms of know-how, which causes trouble for accurate air conditioning control.